Abstract: In early stage of safety critical system development, traditional hazard analysis is inaccurate and incomplete. To overcome the shortcomings, a SCADE (safety critical application development environment) model-based approach to functional hazard analysis (FuHA) is proposed. The SCADE data flow was used to construct system functional architecture model and function fault model, and then that two models were integrated into one model. Based on SCADE, the integrated model was analyzed by the way of implementing a risk scenario capturing algorithm and the system safety critical functions and hazards could be identified. The approach is applied to computer based interlocking system in railway signaling application. The simulation result shows that it can increase the precision and completeness for FuHA.